Effect of calcium compounds on direct reduction and phosphorus removal of high-phosphorus iron ore

Abstract

The increasing demand for iron ore in the world causes the continuous exhaustion of magnetite resources. The utilization of high-phosphorus iron ore becomes the focus. With calcium carbonate (CaCO₃), calcium chloride (CaCl₂), or calcium sulfate (CaSO₄) as additive, the process of direct reduction and phosphorus removal of high-phosphorus iron ore (phosphorus mainly occurred in the form of Fe₃PO₇ and apatite) was studied by using the technique of direct reduction-grinding-magnetic separation. The mechanism of calcium compounds to reduce phosphorus was investigated from thermodynamics, iron metallization degree, mineral composition and microstructure. Results showed that Fe₃PO₇ was reduced to elemental phosphorus without calcium compounds. The iron-phosphorus alloy was generated by react of metallic iron and phosphorus, resulting in high phosphorus in reduced iron products. CaCO₃ promoted the reduction of hematite and magnetite, and improved iron metallization degree, but inhibited the growth of metallic iron particles. CaCl₂ strengthened the growth of iron particles. However, the recovery of iron was reduced due to the formation of volatile FeCl₂. CaSO₄ promoted the growth of iron particles, but the recovery of iron was drastically reduced due to the formation of non-magnetic FeS. CaCO₃, CaCl₂ or CaSO₄ could react with Fe₃PO₇ to form calcium phosphate (Ca₃(PO₄)₂). With the addition of CaCO₃, Ca₃(PO₄)₂ was closely combined with fine iron particles. It is difficult to separate iron and phosphorus by grinding and magnetic separation, resulting in the reduced iron product phosphorus content of 0.18%. In the presence of CaCl₂ or CaSO₄, the boundary between the generated Ca₃(PO₄)₂ and the metallic iron particles was obvious. Phosphorus was removed by grinding and magnetic separation, and the phosphorus content in the reduced iron product was less than 0.10%.

Keywords

high-phosphorus iron ore / direct reduction / calcium compounds / phosphorus removal / calcium phosphate tribasic

References

[1] YuW, TangQ-Y, ChenJ-A, et al.. Thermodynamic analysis of the carbothermic reduction of a high-phosphorus oolitic iron ore by FactSage [J]. International Journal of Minerals Metallurgy and Materials, 2016, 23(10): 1126-1132

[2] SunY-S, HanY-X, GaoP, et al.. Growth kinetics of metallic iron phase in coal-based reduction of oolitic iron ore [J]. ISIJ International, 2016, 56(10): 1697-1704

[3] ChengC, XueQ-G, WangG, et al.. Phosphorus migration during direct reduction of coal composite high-phosphorus iron ore pellets [J]. Metallurgical and Materials Transactions B, 2016, 47(1): 154-163

[4] ChaJ W, KimD Y, JungS M. Distribution behavior of phosphorus and metallization of iron oxide in carbothermic reduction of high-phosphorus iron ore [J]. Metallurgical and Materials Transactions B, 2015, 46: 2165-2179

[5] IonkovK, GaydardzhievS, AraujoA C, et al.. Amenability for processing of oolitic iron ore concentrate for phosphorus removal [J]. Minerals Engineering, 2013, 46–47: 119-127

[6] YuW, SunT-C, KouJ, et al.. The function of Ca(OH)₂ and Na₂CO₃ as additive on the reduction of high-phosphorus oolitic hematite-coal mixed pellets [J]. ISIJ International, 2013, 53(3): 427-433

[7] WangH-H, LiG-Q, YangJ, et al.. The behavior of phosphorus during reduction and carburization of high-phosphorus oolitic hematite with H₂ and CH₄ [J]. Metallurgical and Materials Transactions B, 2016, 47(4): 2571-2581

[8] SunY-S, GaoP, HanY-X, et al.. Reaction behavior of iron minerals and metallic iron particles growth in coal-based reduction of an oolitic iron ore [J]. Industrial and Engineering Chemistry Research, 2013, 52(6): 2323-2329

[9] LiY-J, WangR, HanY-X, et al.. Phase transformation in suspension roasting of oolitic hematite ore [J]. Journal of Central South University, 2015, 22(12): 4560-4565

[10] LuoL-Q, ZhangH-Q. Process mineralogy and characteristic associations of iron and phosphorus-based minerals on oolitic hematite [J]. Journal of Central South University, 2017, 24(9): 1959-1967

[11] ZhouW-T, HanY-X, SunY-S, et al.. Strengthening iron enrichment and dephosphorization of high-phosphorus oolitic hematite using high-temperature pretreatment [J]. International Journal of Minerals Metallurgy and Materials, 2020, 27(4): 443-453

[12] HanY-X, LiG-F, GaoP, et al.. Reduction behaviour of apatite in oolitic haematite ore using coal as a reductant [J]. Ironmaking and Steelmaking, 2017, 44(4): 287-293

[13] KhassenB, BaltynoveN, DakhnoL. Investigation of dephosphorization of brown iron ore concentrates by sintering and magnetic beneficiation [J]. International Journal of Mineral Processing, 2014, 126: 136-140

[14] LiuY-Q, ZhangH, LiZ-E, et al.. Impact of slag composition activity on the behavior of phosphorus in the smelting reduction process of high-phosphorus iron ores [J]. International Journal of Hydrogen Energy, 2017, 42(38): 24487-24494

[15] ZhangH-Q, ZhangZ-Q, LuoL-Q, et al.. Behavior of Fe and P during reduction magnetic roasting-separation of phosphorus-rich oolitic hematite [J]. Energy Sources, 2019, 41(1–6): 47-64

[16] YangC-C, ZhuD-Q, PanJ, et al.. Simultaneous recovery of iron and phosphorus from a high-phosphorus oolitic iron ore to prepare Fe-P alloy for high-phosphorus steel production [J]. JOM, 2017, 69(9): 1663-1668

[17] LiG-H, RaoM-J, OuyangC-Z, et al.. Distribution characteristics of phosphorus in the metallic iron during solid-state reductive roasting of oolitic hematite ore [J]. ISIJ International, 2015, 55(11): 2304-2309

[18] SunY-S, HanY-X, GaoP, et al.. Distribution behavior of phosphorus in the coal-based reduction of high-phosphorus-content oolitic iron ore [J]. International Journal of Minerals Metallurgy and Materials, 2014, 21(4): 331-338

[19] LiY-L, SunT-C, KouJ, et al.. Study on phosphorus removal of high-phosphorus oolitic hematite by coal-based direct reduction and magnetic separation [J]. Mineral Processing and Extractive Metallurgy Review, 2014, 35(1): 66-73

[20] YuW, SunT-C, CuiQ. Can sodium sulfate be used as an additive for the reduction roasting of high-phosphorus oolitic hematite ore? [J]. International Journal of Mineral Processing, 2014, 133: 119-122

[21] SunY-S, ZhangQ, HanY-X, et al.. Comprehensive utilization of iron and phosphorus from high-phosphorus refractory iron ore [J]. JOM, 2017, 70(2): 144-149

[22] YuW, SunT-C, LiuZ-Z, et al.. Effects of particle sizes of iron ore and coal on the strength and reduction of high phosphorus oolitic hematite-coal composite briquettes [J]. ISIJ International, 2014, 54(1): 56-62

[23] ZhuD-Q, ChunT-J, PanJ, et al.. Upgrading and dephosphorization of Western Australian iron ore using reduction roasting by adding sodium carbonate [J]. International Journal of Minerals Metallurgy and Materials, 2013, 20(6): 505-513

[24] QuastK. A review on the characterisation and processing of oolitic iron ores [J]. Minerals Engineering, 2018, 126: 89-100

[25] LuoL-Q, WuY-Q. Current situation of mineral processing and phosphorus removal of refractory oolitic hematite [J]. Journal of Kunming University of Science and Technology (Natural Science Edition), 2015, 40(6): 23-30(in Chinese)

[26] ZhaoY-Q, SunT-C, ZhaoH-Y, et al.. Effects of CaCO₃ as additive on coal-based reduction of high-phosphorus oolitic hematite ore [J]. ISIJ International, 2018, 58(10): 1768-1774

[27] LiG-H, ZhangS-H, RaoM-J, et al.. Effects of sodium salts on reduction roasting and Fe-P separation of high-phosphorus oolitic hematite ore [J]. International Journal of Mineral Processing, 2013, 124: 26-34

[28] RaoM-J, OuyangC-Z, LiG-H, et al.. Behavior of phosphorus during the carbothermic reduction of phosphorus-rich oolitic hematite ore in the presence of Na₂SO₄ [J]. International Journal of Mineral Processing, 2015, 143: 72-79

[29] XuY, SunT-C, LiuZ-G, et al.. Dephosphorization effect of sodium carbonate in the process of direct reduction roasting of high phosphorous oolitic hematite [J]. Journal of Northeastern University (Natural Science), 2014, 35(7): 1028-1032(in Chinese)

[30] ChengC Y, MisraV N, CloughJ, et al.. Dephosphorisation of Western Australian iron ore by hydrometallurgical process [J]. Minerals Engineering, 1999, 12(9): 1083-1092

[31] YangM, ZhuQ-S, FanC-L, et al.. Roasting-induced phase change and its influence on phosphorus removal through acid leaching for high-phosphorus iron ore [J]. International Journal of Minerals Metallurgy and Materials, 2015, 22(4): 346-352

[32] HuangW-S, YanL, WuS-C, et al.. Study on the process mineralogy of a high phosphorus oolitic iron ore in abroad [J]. Metal Mine, 2020, 9: 137-141(in Chinese)

[33] WU Shi-chao, SUN Ti-chang, YANG Hui-fen. Study on phosphorus removal of high-phosphorus oolitic hematite abroad by direct reduction and magnetic separation [J]. Metal Mine, 2019(11): 109–114. DOI: https://doi.org/10.19614/j.cnki.jsks.201911019. (in Chinese)

[34] WU Shi-chao, SUN Ti-chang, KOU Jue, et al. Influence of sodium salts on reduction roasting of high-phosphorus oolitic iron ore [J]. Mineral Processing and Extractive Metallurgy Review, 2021: 1979540. DOI: https://doi.org/10.1080/08827508.2021.1979540.

[35] SunY-S, LiY-F, WangD-Z, et al.. Thermodynamic analysis of the reduction process of fluorapatite [J]. Journal of Northeastern University (Natural Science), 2019, 40(6): 118-123(in Chinese)

[36] YangMDephosphorization mechanism of the raw and as-roasted Huiming high phosphorus limonite through sulfuric acid leaching [D], 2015, Beijing, Institute of Process Engineering, Chinese Academy of Sciences(in Chinese)

[37] ZhouS-W, WeiY-G, LiB, et al.. Chloridization and reduction roasting of high-magnesium low-nickel oxide ore followed by magnetic separation to enrich ferronickel concentrate [J]. Metallurgical and Materials Transactions B, 2016, 471: 145-153

[38] WangW-W, LiZ-Y. Recovery and kinetics of gold and iron from cyanide tailings by one-step chlorination-reduction roasting [J]. Minerals Engineering, 2020, 155(3): 106453

[39] LiX-H, KouJ, SunT-C, et al.. Effects of calcium compounds on the carbothermic reduction of vanadium titanomagnetite concentrate [J]. International Journal of Minerals Metallurgy and Materials, 2020, 273301-309

[40] WuS-C, LiZ-Y, SunT-C, et al.. The mechanism of CaCO₃ in the gas-based direct reduction of a high-phosphorus oolitic iron ore [J]. Physicochemical Problems of Mineral Processing, 2021, 57(4): 117-124